In the prior art, there is a system in which a plurality of reflectors are disposed along the travelling path, and the reflectors are recognized by means of a laser scanner on an automatic guided vehicle to calculate their present position. When three reflectors can be recognized, the present position can be calculated using the principle of triangulation, therefore, the problem with this approach is that concerning whether such recognized reflector is to be specified which of the reflectors on the reflector map. In this case, this problem can be easily solved by assigning identification data such as bar codes to the reflectors, however, such reflectors are expensive and require much time to install. Therefore, in general, the reflectors must be identical.
In order to specify a reflector without assigning identification data to the reflector itself, the start position of an automatic guided vehicle is input to the automatic guided vehicle. First, presuming that the automatic guided vehicle starts from a known position, the recognized reflector is specified at the starting time. In subsequent recognition, the present position is assumed based on the previous recognized position, and to specify the reflectors, the laser scanner is assumed to have recognized those reflectors that can be recognized at the present position. However, when using this technique, if a reflector is incorrectly recognized, it becomes impossible to recognize the exact position of the automatic guided vehicle, thus making it uncontrollable.
It is an object of the present invention to specify reflectors without temporarily determining the present position of the automatic guided vehicle.
It is an additional object of the present invention to enable even newly appeared reflectors to be specified.
It is an additional object of the present invention to have a capability of determining the velocity and angular velocity of the automatic guided vehicle, as well as its position and orientation.